Vegetable Gardening (110 page)

Their slow release of nutrients, in some cases dependent on the action of soil microorganisms, may take too long to remedy a dire situation when an adequate nutrient supply is needed.

Many organic fertilizers are lower in nutrient content than their chemical equivalents, and the contents may vary depending on the weather and conditions where the fertilizers were produced. So you may not be exactly sure how much to put on your garden.

Chemical fertilizers

Chemical fertilizers
are synthetically manufactured. They include elements such as sodium nitrate, potassium chloride, and superphosphate. Chemical fertilizers come in liquid, granular, powder, or pellet form. You can fertilize when you water with a watering can, using a liquid fertilizer. Or you can sprinkle some granular fertilizer around each plant.

Chemical fertilizers are widely available, less expensive than organic fertilizers, quick acting, and easy to use, but I believe that the disadvantages of using chemical fertilizers far outweigh the advantages. Here's why:

Chemical fertilizers add no organic matter to your soil and contribute nothing to improving soil structure.
In fact, some research suggests that chemical fertilizers actually harm the microorganisms in the soil, making the soil less able to support long-term plant growth.

Chemical fertilizers are concentrated and fast acting, but they have no long-term benefits for your soil.
It's like taking a vitamin for your health versus eating a good meal.

Manufacturing chemical fertilizers requires large amounts of energy, usually supplied by nonrenewable resources.
This massive use of energy increases pollution, global warming, and our carbon footprint. Even though some commercial organic fertilizers, such as rock phosphate and green sand, also are manufactured and require energy inputs, home gardeners can instead choose to use locally made compost and manures to get the nutrients they need for their gardens.

Side-dressing

Depending on the crops you grow and the type of soil you have, you may need to add repeat doses of fertilizer throughout the growing season — a practice called
side-dressing.
For example, because sandy soils don't hold nutrients well, giving plants small, regular fertilizer applications ensures a steady supply of nutrients.

In the following sections, I describe specific fertilizers and methods that are best for side-dressing and explain how frequently you should side-dress your veggies. For information on fertilizing vegetables growing in containers, see Chapter 18.

Fertilizers and techniques that work well for side-dressing

Granular organic fertilizers, such as 5-5-5, are a good choice for side-dressing most root and fruiting crops. Use 1 to 2 tablespoons per plant, or 1 to 2 pounds for every 25 feet in a row.

Depending on plant spacing, side-dress either in a narrow furrow down a row or around each individual plant (refer to Figure 15-6). In either case, spread granular fertilizer (which is easier to use than liquid fertilizer) at least 6 to 8 inches away from plant stems. Rake the fertilizer into the soil and then water.

For leafy green crops, fish emulsion is a quick-acting, highly soluble organic source of nitrogen that gives your greens a boost, especially if they're turning a pale green color. You can add micronutrients to this fertilizer by mixing it with seaweed. Add this liquid fertilizer to your watering can following the directions on the label. As you water, pour this solution around the bases of the plants and on the leaves.

Knowing when to side-dress

Too much fertilizer can be more harmful than too little. Excess fertilizer accumulates in the soil in the form of salts and damages plant roots. So be sure that growing conditions enable plants to use the fertilizer that you apply. For example, don't add fertilizer during a dry spell if you can't irrigate your garden, because without adequate soil moisture, roots can't take up nutrients. And if cool weather causes your plants to grow slowly and need less fertilizer, go easy on the fertilizer until the temperature warms up or you'll be wasting it.